In operations involving the drilling of vertical, directional, or horizontal wells, there is a need for accurately controlling the weight of the drill string on a drill bit.
The need to accurately control the weight of the drill string on the rotary drill bit is particularly critical when drilling either directional or horizontal wells. In directional or horizontal wells, the weight on the drill bit affects the angular deviation of the drilled hole away from the vertical. By obtaining an accurate time measurement of the duration of travel of the rotary drill bit within the well bore, together with providing a way of accurately limiting the loads that drillers can place on a rotary drill assembly, it is possible to execute delicate and sophisticated drilling operations while minimizing down hole tool failures and maximizing the life of the rotary drill bit.
While a variety of complex systems have been proposed for controlling the weight on a rotary drill bit, the need remains for a simple, easy-to-use, easy-to-maintain system that allows drillers to execute delicate and sophisticated drilling operations while at the same time minimizing down hole tool failures and maximizing the life of expensive drill bit assemblies.